This invention relates to a base for fastening and carrying thereon an underwater camera contained inside a waterproof camera housing as it is being used for flash lighting, serving to attach thereto an arm having an external flash light provided at its tip.
External flash lamps are used in underwater photography because the quantity of available light is often insufficient. Since water contains small dust particles such as grains of sand as well as planktons that float around, external lamps are often placed away from a camera with its waterproof housing that surrounds it (hereinafter referred as an “underwater camera”) by distances of from ten and some centimeters to several tens of centimeters such that these dust particles, etc. will not appear conspicuously on the obtained image. For this reason, it has been known (as disclosed, for example, in Japanese Patent Publication Tokkai 11-237688) not only to fasten an underwater camera to a base but also to provide an external flash lamp at the tip of an arm and to connect the arm and the base together. In such a case, the base is a planar member to be screwed to the bottom of the housing of the underwater camera. In certain situations, a grip may be provided between the arm and the base.
FIG. 1 is a diagonal view for showing the structure of a conventional base for a general-purpose underwater camera, and FIG. 2 is a diagonal view for showing the manner in which the base of FIG. 1 may be attached to the underwater camera. For the sake of convenience, the main body of the camera is omitted in FIGS. 1 and 2, and the arm is not included in FIG. 2.
In these figures, numeral 1 indicates the base, numeral 2 indicates the waterproof camera housing (hereinafter also referred to simply as the housing), and numeral 3 indicates an arm. The bottom of the housing 2 is provided with a pedestal 4 with a screw hole 6 formed therethrough for attachment with a fixing screw 5. Leg structures 7A and 7B are further provided to the right-hand and left-hand sides of the bottom of the housing 2 for stabilizing the underwater camera.
The base 1 has an elongated hole 8 therethrough for passing therethrough the fixing screw 5 such that only its axial part (that is, the screw part and the cylindrical part that is continuously connected to it) can be freely moved in the direction of the width (hereinafter referred to as the “transverse direction”), depending on the type of the housing 2 that is being used. A protrusion 9 with a specified length is also provided at one end part of the base 1 in the direction of the width for the purpose of positioning the housing 2.
When the housing 2 is affixed to the base 1 thus structured, the axial part of the fixing screw 1 is firstly passed through the elongated hole 8 of the base 1 from below. While the tip of the fixing screw 5 has been somewhat inserted into the screw hole 6 of the housing 2, the housing 2 is moved in the direction of the width of the base 1 for its positioning by pressing the back walls of the leg structures 7A and 7B against the protrusion 9 of the base 1. After the positioning is completed, the fixing screw 5 is fully inserted into the screw hole 6. FIG. 1 shows the fully affixed condition thus achieved.
The housing 2 may be attached to the base 1 backward, as shown in FIG. 3, or in the reversed direction as compared to the attachment explained above. In this situation, the front wall of the pedestal 4 on the housing 2 comes to contact the protrusion 9 for the positioning of the housing 2.
The positioning as described above is necessary because the structure of the housing 2 varies according to the type of the camera that is being used and hence the distance between the screw hole 6 and the protrusion 9 of the base 1 or the front wall of the pedestal 4 also varies. In order to use as a general-purpose base, it is necessary that these distances be adjustable according to the type of the housing 2.
The conventional general-purpose base 1 as described above had many problem points. For example, as the user holds the housing 2 in water for underwater photography, the position of the external flash lamp must be adjusted according to the target object to be photographed if flash lighting is required. The user will carry out this adjustment by varying the angle of the external flash lamp at the tip of the arm 3 affixed to the base 1. Since the arm 3 and the external flash lamp attached to its tip are quite heavy, however, the housing 2 tends to easily undergo a rotational displacement around the leg structures 7A and 7B or the pedestal 4 in contact with the protrusion 9 of the base 1, as shown in FIG. 4. If the housing 2 thus undergoes a rotational displacement, the fixing screw 5 in contact with the bottom surface of the base 1 also rotates by the same amount, becoming loose. This makes it still easier for the housing 2 to rotate, thereby initiating a vicious cycle.
In view of this problem, it has recently been proposed to prevent the rotational displacement of the housing 2 by pasting a frictional sheet of a rubber material on the surface of the base 1 where the bottom part of the pedestal 4 of the housing 2 comes into contact such that the rotational displacement of the housing 2 can be prevented. Since the arm 3 and the external flash lamp at its tip are very heavy, however, this approach has been proved insufficient for dependably preventing the rotational displacement. Since this problem of preventing rotational displacement is distracting to the user from concentrating on the target object to be photographed, there has been a significant demand for an improvement.
Another problem associated with the conventional general-purpose base 1 has been that the loosened screw must be tightened frequently while the user is holding the equipment while being engaged in underwater photography, causing a significant stress on the user while diving.